1. Field of the Invention
The invention relates to a vehicle seat and a coupling method for use in the vehicle seat. More particularly, the invention relates to a vehicle seat in which a side frame of a seat cushion and a floor-side seat supporting member are coupled to each other by a coupling bracket, and a coupling method for use in the vehicle seat.
2. Description of Related Art
A vehicle seat provided in a vehicle such as an automobile (hereinafter simply referred to as “a seat” sometimes) is usually constituted of a seat cushion which is a seat section of a seated occupant, and a seat back which supports the back of the seated occupant. Furthermore, a seat slide rail mechanism is disposed as a floor-side seat supporting member between a floor and the seat so that a position of the seat with respect to the vehicle floor can be adjusted. In the seat slide rail mechanism, an upper rail disposed on a seat cushion side is slidably fitted in a lower rail disposed on a floor side. Such a vehicle seat is described in, for example, Japanese Patent Application Publication No. 2012-30634 (JP 2012-30634 A).
The seat cushion in the seat having the seat slide rail mechanism as described above and the seat slide rail mechanism are coupled to each other by a coupling bracket which couples a side frame forming a framework of the seat cushion to the upper rail of the seat slide rail mechanism. At this time, the side frame and the coupling bracket are usually coupled to each other by arc welding. As shown in FIG. 6, a side frame 118 and a coupling bracket 130 in the form of plates are overlapped with each other, and edge portions X1 and X2 of the side frame 118 and the coupling bracket 130 which are overlapped with each other are arc-welded to join both the side frame and the coupling bracket to each other. That is, the side frame 118 and the coupling bracket 130 are welded in two portions for coupling the side frame 118 and the coupling bracket 130.
When the side frame 118 and the coupling bracket 130 are coupled to each other, the coupling bracket 130 may be disposed at an outer position or an inner position of the side frame 118, in a width direction of the seat. In this case, when welding operation is performed on two portions according to the abovementioned usual method, one of welded portions is formed in an outer part of the side frame 118.
As shown in FIG. 6, when the two edge portions of the side frame 118 and the coupling bracket 130 which are overlapped with each other are welded, welding operation directions, from which the welding operations for the two edge portions are performed, are opposite to each other. That is, the portion X1 at the edge of the side frame 118 is welded from the right side in FIG. 6, and the portion X2 at the edge of the coupling bracket 130 is welded from the left side in FIG. 6.
Therefore, when the welding operation to couple the side frame 118 to the coupling bracket 130 is performed, an operation for reversing a combination body of the side frame 118 and the coupling bracket 130 is required. Therefore, in a flow operation of a mass production line, a jig may be complicated, and that time may increase.